There has been a growing need to expand infrared radiometric investigations from military and space applications to areas such as the thermal behavior of glass, plastics, oils, flames and other substances whose infrared characteristics vary with thickness, composition and wavelength. Unfortunately, potential industrial and academic investigators have not had the funds available to their military and aerospace counterparts. The need, then, was for a multispectral instrument specifically designed for the infrared which would be stable, absolutely calibrated and versatile enough to accomplish the above measurement tasks, yet affordable to the industrial or academic researcher. This paper traces the development of the 12-880 Precision Filter Radiometer which developed as a reconfiguration and expansion of a standard dedicated infrared thermometer. The instrument's unique, highly stable thermal/optical design made this development possible. Several proven applications are discussed as well as a number of potential applications for the new instrument.